Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

Transient Stability Enhancement by Fuzzy Logic-Controlled SMES Considering Coordination With Optimal Reclosing of Circuit Breakers

Abstract: This paper aims at investigating the effect of the coordination of fuzzy logic-controlled superconducting magnetic energy storage (SMES) and optimal reclosing on the transient stability in a simulated multi-machine power system during unsuccessful reclosing of circuit breakers. The performance of the coordinated operation of fuzzy logic-controlled SMES and optimal reclosing is compared to that of the coordinated operation of fuzzy logic-controlled SMES and conventional auto-reclosing. Also, the performance of the fuzzy logic-controlled SMES is compared to that of an alternative static nonlinear controlled SMES. The control scheme of SMES is based on a pulse width modulation (PWM) voltage source converter (VSC) and a two-quadrant dc-dc chopper using gate-turn-off (GTO) thyristor. The parameters of the proposed fuzzy logic controller are optimally tuned by the genetic algorithm (GA) method. Simulation results of both balanced and unbalanced faults at different points in a multi-machine power system show that the coordinated operation of fuzzy controlled SMES and optimal reclosing is able to stabilize the system well in case of an unsuccessful reclosing. Moreover, the transient stability performance of the coordinated operation of fuzzy controlled SMES and optimal reclosing is better than that of the coordinated operation of fuzzy controlled SMES and conventional auto-reclosing. Also, the performance of the fuzzy logic-controlled SMES is better than that of the static nonlinear controlled SMES.

The impact of HIV-related stigma on older and younger adults living with HIV disease: does age matter?

Abstract: The purpose of this study was to examine the independent influence of age on levels of HIV-related stigma experienced by adults living with HIV/AIDS. To accomplish this, cross-sectional data from the Ontario HIV Treatment Network Cohort Study were used to determine whether older age is associated with overall stigma among HIV-positive adults living in Ontario, Canada (n = 960). The relationship was also tested for enacted, anticipated, and internalized stigma. Covariates included sociodemographic (e.g., gender, sexual orientation, race) and psychosocial variables (e.g., depression). Modifying effects of covariates were also investigated. Those 55 and older have significantly lower overall and internalized stigma than adults under age 40, even when accounting for gender, sexual orientation, income, time since diagnosis, depression, maladaptive coping, and social support. Age does not predict enacted or Anticipated Stigma when accounting for the demographic and psychosocial variables. A significant interaction between depression and age suggests that stigma declines with age among those who are depressed but increases to age 50 and then decreases in older age groups among those who are not depressed. Age matters when it comes to understanding stigma among adults living with HIV/AIDS; however, the relationship between age and stigma is complex, varying according to stigma type and depression level.

A Critical Reflection on the Use of Translators/Interpreters in a Qualitative Cross-Language Research Project

Abstract: Based on experiences from a qualitative research project on immigrant women's English language acquisition, we critiqued the traditional positivist model, and identified a number of issues related to the engagement of translators/interpreters in community-based research. The issues that we identified amount to serious questions about ambiguities and ownership of translated language content; assumptions about community familiarity and cultural similarity between researchers, translators, and participants; negotiation of power and authority in the research process; and the risks faced by translators. In the end, though individual research team members bear responsibility over these shortcomings and need to strive to make our research practices more inclusive and equitable, the institutional context of research imposes severe limitations on the ideal alternative model of working with translators and interpreters as co-researchers.

Attitude Coordination Control for a Group of Spacecraft Without Velocity Measurements

Abstract: This paper investigates the problem of velocity-free attitude coordination control for a group of spacecraft with attitude represented by modified Rodrigues parameters. The communication flow among neighbor spacecraft is described by an undirected connected graph. Two velocity-free attitude coordination control schemes are proposed. By employing linear reduced-order observers, robust control and Chebyshev neural networks, the first velocity-free control scheme allows a group of spacecraft to simultaneously align their attitude and track a time-varying reference attitude even in the presence of unknown mass moment of inertia matrix and external disturbances, where all spacecraft have access to the common reference attitude. The second control law guarantees a group of spacecraft to track a time-varying reference attitude without requiring velocity measurements even when the common reference attitude is available only to a subset of the group members. Furthermore, the stability of the overall closed-loop system for both control laws is guaranteed by a Lyapunov-based approach. Finally, numerical simulations are presented to demonstrate the performance of the proposed controllers.